Abrasive wheel



April 16, 1940. M. M. BOUCHER ABRASIVE WHEEL Filed March 2, I939 3mm MFILCDLM M. BUUEJHEH Patented Apr. 16, 1940 PATENT OFFICE ABRASIVE WHEEL Malcolm M. Boucher, Tacoma, Wash., assignor to Bohr-Manning Corporation, Troy, N. Y., a corporation of Massachusetts Application March 2, 1939, Serial No. 259,312

I 1 Claim.

The invention relates to abrasive wheels, and with regard to its specific features to a joiner for joining the ends of a piece of coated abrasive to form the covering for a polishing wheel or the like.

One object of the invention is to provide a polishing wheel whose abrasive action is substantially uninterrupted. Another object of the invention is to provide a simple device for covering a polishing wheel with coated abrasive material without leaving a joint which will bump the work as the work is held against the polishing wheel. Another object of the invention is to provide a simple abrasive band joiner facilitating the coveringof polishing wheels with coated abrasive material. Another object of the invention is to provide an improved polishing wheel of the expansible type. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, arrangements of parts, and in the several steps and relation and order of each of said steps to one or more of the others thereof, all as will be 5 illustratively described herein, and the scope of I the application of which will be indicated in the following claim.

In the accompanying drawing illustrating one of many possible embodiments of the mechanical features of this invention:

Figure 1 is an axial sectional view of an expansible polishing wheel to which the abrasive band and joiner of the present invention may be applied Figure 2 is an end elevation of a polishing wheel, showing an abrasive band thereon with its ends held together by the joiner of the present invention which is located in a recess formed in the wheel;

40 Figure 3 is a fragmentary sectional view, on an enlarged scale, of the periphery of the polishing wheel at the point where it is recessed to receive the joiner, illustrating also the joiner and a fragment of the coated abrasive material;

5 Figure 4 is a plan view of the joiner;

Figure '5 is an end view of the joiner;

Figure 6 is a side elevation of the polishing wheel after the coated abrasive has been placed on it, showing the joiner being inserted in the 50 recess; and

Figure 7 is a perspective view of an anvil member, illustrating the manner of preparing the coated abrasive material for cooperation with the joiner.

55 Referring first to Figure 1, I have therein illustrated an expansible polishing wheel. Such a wheel may comprise a cylindrical block of rubber Ill having countersunk flanges II and I2 located in corresponding countersunk recessed portions in the ends of the block of rubber, which 5 is provided with a central axial bore I3. The expansible wheel may be mounted upon an armature shaft I4 of an electric motor, not shown,

or the shaft I4 may be rotated in any other desired manner. ed with an enlarged diameter portion I5 which abuts the flange H. To the right of the enlarged diameter portion I5 is a cylindrical portion I6 of the shaft I4 which just fits within the bore I3. Beyond the portion I6 to the right thereof 15 is a slightly reduced diameter portion I! of the shaft I4 fitting a similarly reduced diameter portion I8 of the bore I3. The right-hand end of the shaft I4 is drilled and tapped and receives a bolt 20 which may be forced against a large 30 bushing 2| which is permanently fastened to the recessed flange I2. vA washer 22 is preferably interposed between the head of the bolt 20 and the bushing 2I'.

If now the cylindrical rubber block with its 5 flanges II and I2 be placed upon the shaft I4, as shown in Figure 1, and the bolt 20 be tightened, the rubber will be squeezed together by the flanges II and I2 which will cause the rubber to expand. The rubberblock I0 acts as a support 3 for an endless band of coated abrasive material which is of a size to fit easily over the rubber block II] when the bolt 20 is loosened; the bolt 20 may then be tightened which expands the rubber inside of the endless band, thus holding the band firmly in place. This makes an effective polish-- ing wheel because the abrasive is supported by a resilient backing,'yetit is firmly held to this backing and the removal of a used abrasive band and replacement thereof with a new one may be 40 quickly accomplished.

Various expedients have heretofore been adopted for forming endless bands out of coated abrasive material, but most of these have been open to the objection of forming a seam so that the covered article has a bump in its periphery. When polishing or abrading with a rotatable abrasive article having a pronounced seam or a bump or a ridge, there is a tendency for the ridge to do most of the abrading until the abra- 5o sive grains are worn therefrom, and thereupon the underlying paper or cloth quickly wears out and the entire endless band has to be discarded before the useful-life of its major portion is utilized. 1

The shaft I4 is shown as providl0 able length of coated abrasive material of any desired type. This may be paper or cloth coated with any suitable abrasive, such as silicon carbide or any other hard carbide, garnet, quartz, crushed glass, alumina in any of its forms including fused alumina, emery or corundum. I

select a width of the coated abrasive material which is the same as the length of the block III,

or if such width be not readily available, I cut out.

a long strip of material of such width. I then carefully calculate the length of the abrasive material which should be equal to the circumference of the block I0 in its collapsed condition, plus twice the inside length of a portion 32. I then cut the abrasive material to this length or slightly more or less. Referring now to Figure '7, I provide an anvil 35 which may consist of a piece of wood or metal, generally rectangular in shape, and having a groove 36 in its upper edge, the anvil member 35 having sharp corners. This anvil member 35 is preferably of a length at least equal to the width of the coated abrasive material to be used to cover the block Ill. The depth of the groove 36 plus the width of that part of the upper portion of the anvil 35 which extends between the groove 36 and a side wall 31 is just slightly less than the inside length of a portion 32. I now place the end of the coated abrasive material in the groove 36 and bend the abrasive material over, as shown in Figure '7. With a metal rod, the back of a knife blade or any other instrument, I then scrape off the abrasive at the line 40, which may readily be done since the coated abrasive material is flexed into a right angle at this point.

The ends of the length of coated abrasive material may now be bent over to form underlapping portions 42, as shown in Figures 2 and 3. I then take the coated abrasive material and place it around the rubber block In with the lines where the abrasive has been scraped off abutting each other and with the underlapping'portions 42 lying in the groove 25. I then slip the end of the joiner 30 into position with the portions 32 between the underlapping pertions 42 and the inside cylindrical surface of the coated abrasive material 45. Figure 6 shows the joiner 30 being slipped into position. When it is inserted all the way into the groove 25, the bolt 20 can be tightened and then the coated abrasive is securely locked onto the rubber block II).

It will now be seen that the rubber block II] has applied thereto a piece of coated abrasive material which is in effect jointless. The joiner 30 fits in the groove 25 with a snug fit, as shown in Figure 3, and there is no bump or elevation or ridge in the surface of the polishing wheel.

for its entire useful life on all portions thereof. When it is desired to replace the abrasive band 45 with a new one, the bolt 20 may be loosened and the joiner 30 then slipped out of position and a new band quickly inserted.

The coated abrasive material may, therefore, be used.

It is contemplated that a great many bands can be cut to the right dimensions and have the abrasive grains scraped off in lines 40 by the apparatus shown in Figure 7 or in any other suitable manner, and then the changing of abrasive bands on the polishing wheels is a matter of but a moment, using the joiner of the present invention. It will be seen that if the joiner 30 should happen to be opened up slightly so as to form anything in the nature of a ridge, it can be quickly closed down by an ordinary pair of plyers or with a vise. Furthermore, the polishing action has a tendency to close the portions 32 onto the portion 3| so there is substantially no danger that a ridge will be formed in the polishing wheel. I have found that the joiner made according to the present invention hods the abrasive very rigidly and there is no tendency of the coated abrasive material to come out from the joiner. Because I remove abrasive material along a given line which fits over an edge of the portion 32, the coated abrasive band is substantially interlocked to the joiner 30.

One particular advantage of the present invention is that the joiner 30 looks or keys the abrasive band to the rubber block or drum III. This prevents the band 45' from slipping and avoids wearing out the drum. A specific feature of value of my joiner is that it can be made very light and in fact it can readily be made so that the weight 'of the joiner plus the extra amount of coated abrasive in the groove 25 is exactly equal to the weight of rubber removed to form said groove, so that the wheel will be in perfect balance. I

Another advantage \of the present invention is that an endless abrasive band can be quickly made up anywhere. I have shown how it can be made up on the drum itself and this is advantageous when a single shaft has a plurality of polishing wheels because premade endless bands cannot readily be placed on the inner whees. So also the existence of shaft hangers is no obstacle to the application of my improved abrasive bands. In many cases I can assemble the band and joiner off the wheel or drum, for example around a shaft next to the drum, and then slide them into position while the drum ,is collapsed.

It will thus be seen that there has been provided by this invention a method and an article in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to be understood thatall matter hereinbefore set forth is to be interpreted as illustrative and not in a limiting sense.

I claim:

A polishing wheel comprising a cylindrical rubber block, metal flanges on' thee'nds of said block, screw means to press the flanges together;

there being a recess in the periphery of the block," 

